ENVIRO TECH CHEMICAL SERVICES, INC. v. SAFE FOODS CORP.

Authored by: Jeremy J. Gustrowsky

The Federal Circuit recently affirmed a district court ruling that invalidated claims of a poultry processing patent owned by Enviro Tech Chemical Services, Inc., finding that the word “about” rendered the claims indefinite. The case centered on U.S. Patent No. 10,912,321, which describes methods for treating poultry carcasses with peracetic acid to increase weight during processing. Enviro Tech had sued Safe Foods Corp. for infringement, but the asserted claims fell apart at the claim construction stage.

The disputed claim language required altering the pH of peracetic acid-containing water to “a pH of about 7.6 to about 10.” While the Federal Circuit acknowledged that words of approximation like “about” and “approximately” are not inherently problematic, it emphasized that such terms must allow a skilled artisan to determine the claim’s scope with reasonable certainty based on the technological facts of the case. Here, the court found that neither the claim language, the specification, nor the prosecution history provided that clarity.

The specification proved particularly troublesome because it sent mixed signals. In most experiments described in the patent, Enviro Tech proceeded only when the actual pH deviated from the target by 0.3 or less. However, in several other examples, including a large commercial trial involving 5.8 million chickens at a major U.S. poultry processor, the company continued experiments with deviations between 0.35 and 0.5 from the target pH. The court found this conflicting guidance prevented a skilled person from pinning down what “about” actually meant.

The prosecution history made matters worse rather than better. Enviro Tech treated the term inconsistently, sometimes including “about” when discussing the claimed pH range and sometimes omitting it, and never explained to the examiner what the word meant. The patentee argued on appeal that its amendment of the lower boundary from “about 7.3” to “about 7.6” should be read as a disclaimer of any deviation greater than 0.3, but the court rejected this theory, noting that no explanatory remarks accompanied the amendment to support such a reading.

A key factor driving the court’s decision was the close proximity of prior art that disclosed a pH of 7.0. Because the specification described pH ranges from 6 to 10 and the claims had to be amended to avoid prior art at pH 7.0, the definiteness requirement of 35 U.S.C. § 112 demanded more precision than the vague term “about” could provide. As the court colorfully put it, the prior art was almost “about” a pH of 7.6. Having affirmed indefiniteness on this ground, the Federal Circuit declined to address the alternative ruling that “an antimicrobial amount” was also indefinite, leaving all asserted claims invalid.